Integrated memory cell array

Abstract

The present invention provides an integrated memory cell array comprising: a semiconductor substrate; a plurality of cell transistor devices including: a pillar formed in said semiconductor substrate; a gate trench surrounding said pillar; a first source/drain region formed in an upper region of said pillar; a gate dielectric formed on the bottom of said gate trench and surrounding a lower region of said pillar; a gate formed on said gate dielectric in said gate trench and surrounding a lower region of said pillar; and a second source/drain region formed in an upper region of said semiconductor substrate adjoining said gate trench; a plurality of bitlines being connected to respective first groups of first source/drain regions of said cell transistor devices; a plurality of wordlines connecting the respective gates of second groups said cell transistor devices; and a plurality of cell capacitor devices being connected to the second source/drain regions of said cell transistor devices.

1. An integrated circuit comprising a memory cell array, comprising:
 a semiconductor body; 
 a plurality of cell transistor devices formed along a plurality of parallel active area stripes of said body, said active area stripes running in a first direction and being laterally insulated from each other by intervening insulation trenches; 
 each of said cell transistor devices comprising:
 a pillar formed in said semiconductor body; 
 a gate trench surrounding said pillar; 
 a first source/drain region formed in an upper region of said pillar; 
 a gate dielectric formed on a bottom of said gate trench and surrounding a lower region of said pillar; 
 a gate formed on said gate dielectric in said gate trench and surrounding a lower region of said pillar; and 
   1 a second source/drain region formed in an upper region of said semiconductor body adjoining said gate trench; 
 
 a plurality of parallel bitlines running in a second direction and being connected to respective second source/drain regions of said cell transistor devices; 
 a plurality of wordlines running in a third direction and connecting the respective gates of said cell transistor devices associated with different bitlines; and 
 a plurality of cell capacitor devices being connected to respective first source/drain regions of said cell transistor devices. 
 
   
   
     2. The integrated circuit comprising the memory cell array according to  claim 1 , wherein each of said cell transistor devices comprises a channel formed in the semiconductor body below the gate dielectric which has a curved upper surface in a direction perpendicular to a current flow direction. 
   
   
     3. The integrated circuit comprising the memory cell array according to  claim 1 , wherein said pillar has curved sidewalls. 
   
   
     4. The integrated circuit comprising the memory cell array according to  claim 1 , wherein each of said cell transistor devices comprises a channel formed in the semiconductor body below the gate dielectric which includes upper corners covered by said gate dielectric and gate. 
   
   
     5. The integrated circuit comprising the memory cell array according to  claim 1 , wherein said cell capacitor devices are formed above an associated first source/drain region. 
   
   
     6. The integrated circuit comprising the memory cell array according to  claim 1 , wherein said active area stripes running in the first direction have a zig-zag substructure. 
   
   
     7. The integrated circuit comprising the memory cell array according to  claim 1 , wherein said wordlines are formed by adjacent gates. 
   
   
     8. The integrated circuit comprising the memory cell array according to  claim 1 , further comprising a second pillar defining a second gate trench surrounding the second pillar, a second gate dielectric and a second gate formed in the second trench, wherein the second gate dielectric is disposed between the second gate and the second pillar, wherein each of said cell transistor devices comprises a third source/drain region formed in an upper region of the second pillar formed in said semiconductor body adjoining said gate trench opposite to said first source/drain region, said first and third source/drain regions belonging to two different memory cells which share said second source/drain region and which have adjacent wordlines. 
   
   
     9. The integrated circuit comprising the memory cell array according to  claim 8 , wherein said adjacent wordlines are insulated from another neighboring wordline by a respective insulation region formed in said active area stripe. 
   
   
     10. The integrated circuit comprising the memory cell array according to  claim 1 , wherein said second and third directions are orthogonal to each other and said first direction is oblique to said second and third directions. 
   
   
     11. The integrated circuit comprising the memory cell array according to  claim 10 , wherein said first direction forms an angle of between 15 and 25 degrees with said second direction. 
   
   
     12. An integrated circuit comprising a memory cell array comprising:
 a semiconductor body; 
 a plurality of cell transistor devices comprising;
 a pillar formed in said semiconductor body; 
 a gate trench surrounding said pillar; 
 a first source/drain region formed in an upper region of said pillar; 
 a gate dielectric formed on the bottom of said gate trench and surrounding a lower region of said pillar; 
 a gate formed on said gate dielectric in said gate trench and surrounding a lower region of said pillar; and 
 a second source/drain region formed in an upper region of said semiconductor body adjoining said gate trench; 
 
 a plurality of bitlines being connected to respective first groups of second source/drain regions of said cell transistor devices; 
 a plurality of wordlines connecting the respective gates of second groups of said cell transistor devices; and 
 a plurality of cell capacitor devices being connected to respective first source/drain regions of said cell transistor devices. 
 
   
   
     13. The integrated circuit comprising the memory cell array according to  claim 12 , wherein each of said cell transistor devices comprises a channel formed in the semiconductor body below the gate dielectric which has a curved upper surface in a direction perpendicular to a current flow direction. 
   
   
     14. The integrated circuit comprising the memory cell array according to  claim 12 , wherein said pillar has curved sidewalls. 
   
   
     15. The integrated circuit comprising the memory cell array according to  claim 12 , wherein each of said cell transistor devices comprises a channel formed in the semiconductor body below the gate dielectric which includes upper corners covered by said gate dielectric and gate. 
   
   
     16. The integrated circuit comprising the memory cell array according to  claim 12 , wherein said cell capacitor devices are formed above an associated first source/drain region. 
   
   
     17. The integrated circuit comprising the memory cell array according to  claim 12 , wherein said wordlines are formed by adjacent gates. 
   
   
     18. The integrated circuit comprising the memory cell array according to  claim 12 , further comprising a second pillar defining a second gate trench surrounding the second pillar, a second gate dielectric and a second gate formed in the second trench, wherein the second gate dielectric is disposed between the second gate and the second pillar, wherein each of said cell transistor devices comprises a third source/drain region formed in an upper region of the second pillar formed in said semiconductor body adjoining said gate trench opposite to said first source/drain region, said second and third source/drain regions belonging to two different memory cells which share said second source/drain region and which have adjacent wordlines. 
   
   
     19. The integrated circuit comprising the memory cell array according to  claim 18 , wherein said adjacent wordlines are insulated from another neighboring wordline by a respective insulation region formed in said active area stripe. 
   
   
     20. An integrated circuit comprising a memory cell array, comprising: a plurality of parallel active area stripes formed in a semiconductor body, the active area stripes running in a first direction and being separated from each other by first isolation trenches, the active area stripes each comprising a plurality of pillars comprising a center pillar, a first outer pillar and a second outer pillar, wherein the first and second outer pillars are arranged on opposite sides of the center pillar, and wherein each of the plurality of pillars comprise a source/drain region formed in an upper portion thereof; a plurality of parallel bitlines running in a second direction and connected to the source/drain region of a respective center pillar of the plurality of active area stripes; and a plurality of wordlines running in a third direction, and a plurality of cell capacitor devices connected to the source/drain regions of respective first and second outer pillars, wherein the first and second outer pillars of each group of pillars in an active area stripe are surrounded by gate trenches, wherein each gate trench comprises a gate electrode arranged at a bottom portion of the gate trenches, and a gate dielectric disposed between the gate electrode and the respective pillar, and wherein each group of pillars correspond to two memory cell transistors with a common bitline contact associated with the center pillar, and with gate electrodes connected to adjacent wordlines.